Transmissions and devices for transferring or redirecting motive power are well known in many arts, typically in the form of interconnected driven and driving shafts or gears between a power source and a driven object. The interconnection between the various components of a transmission is made frequently by clutches, whereby the operation and speed of a driven item may be selectively controlled. Such transmissions and clutch mechanisms are disclosed in U.S. Pat. Nos. 2,019,073, 2,232,457 and 4,404,868.
In the material handling arts, U.S. Pat. Nos. 4,480,735 and 3,722,307 disclose that it is known to allocate power to more than one output from a single driving input. The '307 patent discloses a drive system for a manure spreader that includes a main drive shaft operatively connected to a spreading mechanism and a second drive shaft that is drivingly connected to an apron conveyor, wherein torque is transferred from the main drive shaft to the second drive shaft and wherein a clutch collar is keyed and slidable on the second shaft so that one portion of the spreader can be declutched without affecting the other driven portion. Somewhat similarly, U.S. Pat. No. 4,732,330 discloses an implement and drive gearbox wherein the gearbox includes two angularly offset clutches and direct gear drive is provided for one of the assemblies of the implement.
Other power coupling or transmission units for material handling equipment are disclosed in U.S. Pat. Nos. 3,014,729, 3,583,242, 3,887,153 and 3,964,714.
While the above prior art discloses improved transmission and clutch mechanisms for material handling devices, there are some remaining problems. For example, the desirability of enclosing a transmission so that it won't get clogged or filled with mud, ice or the like is suggested in the '868 patent, but accomplishing this while providing a compact, unitary gearbox or transmission housing for containing at least two drive trains is a problem not completely solved by the prior art.
It would be advantageous if a unitary, compact transmission could be provided wherein the gearbox, casing or housing of the transmission is penetrated by a minimum number of drive train connections, shifting linkages, other control linkages or the like. Moreover, a transmission or transfer case, particularly for use on material handling devices such as machines for agricultural use, should be as compact as possible. The width of gates and building doors, in conjunction with the needs for highway safety, hauling a sufficient payload and distributing power effectively, make it desirable to achieve an efficient transfer of power while using a minimum amount of valuable space and weight capacity.
When operating any type of material handling equipment, it would be desirable if the operator is required to manipulate only a limited number of controls or linkages, thereby keeping the hands as free as possible. Additionally, any controls that are provided ideally would require a minimum amount of manipulation to achieve the desired performance parameters of the device being operated.
A transmission should be structurally as simple as possible, thereby decreasing or minimizing maintenance costs and the probability of catastrophic failure.
A gearbox or transmission for use with devices having power driven features, particularly agricultural implements or material handling equipment, having a single operating control for selectively and variably redirecting power from a single input shaft to two output shafts, in a compact and sealed gearbox or transmission housing would be a decided improvement over the transmission and drive mechanisms disclosed in the prior art.